Systems and methods for model parameter optimization in three dimensional based color mapping

ABSTRACT

Systems, methods, and devices are disclosed for performing adaptive color space conversion and adaptive entropy encoding of LUT parameters. A video bitstream may be received and a first flag may be determined based on the video bitstream. The residual may be converted from a first color space to a second color space in response to the first flag. The residual may be coded in two parts separated by the most significant bits and least significant bits of the residual. The residual may be further coded based on its absolute value.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 62/014,610, filed Jun. 19, 2014, and U.S. Provisional PatentApplication Ser. No. 62/017,743, filed Jun. 26, 2014, each of which isentitled “SYSTEMS AND METHODS FOR MODEL PARAMETER OPTIMIZATION IN THREEDIMENSIONAL BASED COLOR MAPPING” and each of which is incorporatedherein by reference in its entirety.

BACKGROUND

In recent years, wireless technologies have been demanding higher datathroughput rates and lower latencies. One common application that drivesthis demand is video rendering on mobile devices (also referred to as“User Equipment” or simply “UE”). Carrier aggregation and multi-RAT(Radio Access Technology) capabilities have been introduced to helpaddress the need for higher data rates demanded by such applications andother services that use large amounts of data. Carrier aggregation mayallow operators to offload some of their data traffic to secondary cells(e.g., transmitted on secondary component carriers). The use ofmulti-RAT technologies, such as RAT aggregation, may allow receptionand/or transmission over multiple RATs, e.g., simultaneously. Such RATsthat may be used together may include Long Term Evolution (LTE) usedwith Wideband Code Division Multiple Access (WCDMA), LTE used with WiFi,etc. In such aggregation approaches an evolved Node B (eNB) and a UE maycommunicate over multiple parallel paths.

Various digital video compression technologies have been developed toassist with efficient digital video communication, distribution, andconsumption. Widely deployed standards include InternationalTelecommunication Union (ITU) coding standards such as H.261, H.263, andH.264, as well as other standards such as MPEG-1, MPEG-2, MPEG-4 part2,and MPEG-4 part 10 Advanced Video Coding (AVC). Another video codingstandard, High Efficiency Video Coding (HEVC), has been developed by theITU-T Video Coding Experts Group (VCEG) and the InternationalOrganization for Standardization/International ElectrotechnicalCommission (ISO/IEC) Moving Picture Experts Group (MPEG). The HEVCstandard may achieve twice the compression efficiency as that possibleusing H.264 and MPEG-4 part 10 AVC. Thus, in terms of bandwidthutilization, HEVC requires half the bit rate of H.264 or MPEG-4 part 10AVC, while providing the same or similar video quality.

As the use of mobile devices, such as smartphones, tablets, etc.,increases, there is a corresponding increased demand for video contentand services over wireless networks. Thus, mobile devices of widelyvarying capabilities in terms of computing power, memory, storage size,display resolution, display frame rate, display color gamut, etc. willbe expected to accommodate video consumption to be successful in today'smobile device market. Likewise, the wireless network with which suchdevices communicate will also be expected to accommodate video servicesand other bandwidth intensive services and applications.

SUMMARY

Systems, methods, and devices are disclosed for decoding 3-dimensionallook-up table parameters for use in video decoding. In an embodiment,methods, systems, and devices may be implemented for decoding3-dimensional look-up table parameters for use in video decoding byreceiving a delta value, most significant bits of a prediction residualvalue, and least significant bits of the prediction residual value. Aprediction residual value may be generated by determining a first valuerepresenting a quantity of fixed-length coded least significant bitsbased on the delta value, determining the least significant bits of theprediction residual value based on the first value, and assembling theprediction residual value using the most significant bits of theprediction residual value and the least significant bits of theprediction residual value. A prediction residual value may be associatedwith one of a Y color component, a U color component, or a V colorcomponent. A sign of a prediction residual value may be received andused to assemble the prediction residual value. Assembling a predictionresidual value may include left bit shifting most significant bits ofthe prediction residual value by a first value, adding least significantbits of the prediction residual value to the prediction residual value,and/or applying a sign of the prediction residual value to theprediction residual value. A prediction residual value may be associatedwith at least one of a color component, a 3-dimensional look-up tableparameter, and a 3-dimensional look-up table octant.

Systems, methods, and devices are also disclosed for encoding3-dimensional look-up table parameters for use in video encoding. In anembodiment, methods, systems, and devices may be implemented for coding3-dimensional look-up table parameters for use in video encoding bydetermining a prediction residual value, determining a delta value basedon a quantity of least significant bits of the prediction residualvalue, and encoding the delta value. The most significant bits and/orthe least significant bits of the prediction residual value may beencoded based on the delta value. Determining a delta value may includedetermining 3-dimensional look-up table data and/or determining a deltavalue based on 3-dimensional look-up table data. Determining a deltavalue may also include determining a first quantity of bits required tocode 3-dimensional look-up table data based on a first delta value,determining a second quantity of bits required to code the 3-dimensionallook-up table data based on a second delta value, and selecting one ofthe first delta value and the second delta value as the delta valuebased on the first quantity of bits and the second quantity of bits.Selecting one of the first delta value and the second delta value may bebased on whether the first quantity of bits is smaller than the secondquantity of bits or the second quantity of bits is smaller than thefirst quantity of bits. Determining a quantity of bits required to code3-dimensional look-up table data based on a delta value may includesumming a quantity of bits required to code model parameters for oneoctant of a 3-dimensional look-up table. A sign of a prediction residualvalue may also be encoded. These and other aspects of the subject matterdisclosed are set forth below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example system for implementing the disclosedembodiments.

FIG. 2 illustrates an example system for implementing the disclosedembodiments.

FIG. 3 illustrates an example graph comparing HDTV and UHDTV in CIEcolor definition

FIG. 4A shows an example image.

FIG. 4B shows another example image.

FIG. 5 illustrates an example system for implementing the disclosedembodiments.

FIG. 6 illustrates an example 3D LUT-based mapping according to anembodiment.

FIG. 7 illustrates an example 3D LUT-based mapping according to anembodiment.

FIG. 8 illustrates an example prediction structure according to anembodiment.

FIG. 9 illustrates another example prediction structure according to anembodiment.

FIG. 10 illustrates an example method of implementing the disclosedembodiments.

FIG. 11A is a system diagram of an example communications system inwhich the disclosed subject matter may be implemented.

FIG. 11B is a system diagram of an example wireless transmit/receiveunit (WTRU) that may be used within the communications systemillustrated in FIG. 11A.

FIG. 11C is a system diagram of an example radio access network and anexample core network that may be used within the communications systemillustrated in FIG. 11A.

FIG. 11D is a system diagram of another example radio access network andan example core network that may be used within the communicationssystem illustrated in FIG. 11A.

FIG. 11E is a system diagram of another example radio access network andan example core network that may be used within the communicationssystem illustrated in FIG. 11A.

DETAILED DESCRIPTION

A detailed description of illustrative examples will now be describedwith reference to the various figures. Although this descriptionprovides a detailed example of possible implementations, it should benoted that the details are intended to be exemplary only and in no waylimit the scope of the application.

Various digital video compression technologies may be used to enableefficient digital video communication, distribution, and consumption.Examples of standards that may be used to enable such efficient digitalvideo communication, distribution, and consumption may include thosedeveloped by ISO/IEC and/or ITU-T, such as H.261, MPEG-1, MPEG-2, H.263,MPEG-4 part2, and H.264/MPEG-4 part 10 AVC. HEVC is another example ofsuch a standard. Versions of HEVC have been standardized jointly byITU-T VCEG and the ISO/IEC MPEG. As noted herein, HEVC standards mayachieve twice the compression efficiency as the compression efficiencythat may be achievable with H.264/AVC.

Digital video services may be provided using TV services over satellite,cable, and/or terrestrial broadcasting channels. As the Internet onmobile devices becomes more common with the recent growth of smartphonesand tablets with increased capabilities in resolution, memory, storage,and computation capability, a greater number of video applications(e.g., video chat, mobile video recording and sharing, and videostreaming) may become more common and may require video transmission inheterogeneous environments (i.e., environments that may include devicesof varying capabilities). Devices in such scenarios may be referred toas 3-screen or N-screen devices and may have various types andcapabilities in terms of computing power, memory/storage size, displayresolution, display frame rate, display color gamut, etc. Examples ofsuch devices may include PCs, smart phones, tablets, TVs, etc. Suchdevices may accommodate video consumption via the Internet to satisfyusers.

Network and transmission channels that may facilitate video consumptionmay have widely varying characteristics in terms of, for example, packetloss rate, available channel bandwidth, burst error rate, etc. Becausevideo content traffic may be transmitted over a combination of wirednetworks and wireless networks, the underlying transmission channelcharacteristics may become complicated. In such scenarios, scalablevideo coding technologies may provide an attractive solution that mayimprove the quality of experience for video applications running ondevices with different capabilities over heterogeneous networks.Scalable video coding may encode the signal once at its highestrepresentation (temporal resolution, spatial resolution, quality, etc.)and/or may enable decoding from subsets of one or more video stream(s),in some embodiments depending on a specific rate and/or representationrequested by a given application and/or by a given client device.Scalable video coding may save bandwidth and/or storage compared tonon-scalable solutions. The international video standards MPEG-2 Video,H.263, MPEG4 Visual, and H.264 may each have tools and/or profiles thatsupport at least some modes of scalability.

FIG. 1 is a block diagram illustrating exemplary system 1000 that mayrepresent a block-based hybrid scalable video encoding system. Thespatial/temporal signal resolution to be represented by layer 1 1071(e.g., a base layer) may first be generated by down-sampling 1031 inputvideo signal 1081 and providing it to layer 1 encoder 1001. Quantizersetting Q 1061 may be provided to encoder 1001 to configure encoder 1001to provide a certain quality level of the base layer signal. The layer 11071 encoded signal may be provided to layer 1 decoder 1021 that maygenerate reconstructed video signal 1091. Layer 1 decoder 1021 may beconfigured with quantizer setting 1064 specifying a quality level fordecoding an encoded layer 1 signal.

Base layer reconstructed video signal 1091 may be an approximation ofsome or all of the higher layer resolution levels. Reconstructed videosignal 1091 may be utilized in the encoding and/or decoding ofsubsequent layers to, for example, more efficiently encode thesubsequent higher layers. Upsampling unit 1043 may perform upsampling ofbase layer reconstructed signal 1091 to layer 2 1072's resolution andprovide such an upsampled signal for adding 1054 to a layer 2 1072decoded signal decoded by layer 2 decoder 1022. Layer 2 decoder 1022 maybe configured with quantizer setting 1065 specifying a quality level fordecoding an encoded layer 2 signal. Similar upsampling and signaladdition may be performed throughout some or all layers (e.g., layers 1,2, . . . N) using, for example, signal addition 1055, upsampling 1044,and layer N decoder 1023 to generate reconstructed video signal 1093from layer N 1073 encoded signal generated by layer N encoder 1003.Layer N decoder 1023 may be configured with quantizer setting Q 1066specifying a quality level for decoding a layer N 1073 signal. Note thatdownsampling and upsampling ratios may vary and may be related to adimension of the scalability between two given layers.

In system 1000 of FIG. 1, for any given higher layer n (e.g., layer2≤n≤N), a differential signal may be generated by subtracting anupsampled lower layer signal (e.g., a layer n−1 signal) from a currentlayer n signal and the difference signal may be encoded. If the videosignals represented by two layers, e.g., n1 and n2, have the samespatial resolution, the corresponding downsampling and upsamplingoperations may be bypassed. Any given layer n (e.g., where 1≤n≤N) or aplurality of layers may be decoded without using any decoded informationfrom higher layers. For example, layer 1 encoder 1001 output may bedecoded by layer 1 decoder 1011, upsampled 1041, and subtracted 1051from video signal 1081 that may be downsampled 1032 prior to suchsubtraction. Similarly, layer 2 encoder 1002 output may be decoded bylayer 2 decoder 1012, added 1052 to the signal generated by upsampling1041, upsampled 1042 and subtracted 1053 from video signal at a higherlayer N before encoding at layer N encoder 1003 to generated layer N1073 encoded signal. Note that encoders 1002 and 1003 may use quantizersettings Q 1062 and 1063, respectively, to determine a quality level forencoding a signal. Any other encoders and decoders contemplated hereinmay also use any input, setting, or signal to determine a quality levelfor encoding and/or decoding a signal, and all such embodiments arecontemplated as within the scope of the instant disclosure.

Relying on coding of a residual signal (e.g., a difference signalbetween two layers) for all layers except a base layer, for example asshown in system 1000 of FIG. 1, may result in visual artifacts due toquantization and normalization of such a residual signal to restrict itsdynamic range and additional quantization that may be performed duringcoding of the residual signal. One or more of the higher layer encodersmay adopt motion estimation and/or motion compensated prediction as anencoding mode. Motion estimation and motion compensation in a residualsignal may differ from conventional motion estimation and may be proneto visual artifacts. To minimize such visual artifacts, moresophisticated residual quantization, as well as joint quantizationbetween quantizing and normalizing the residual signal to restrict itsdynamic range and additional quantization performed during coding of theresidual may be used.

Scalable Video Coding (SVC) may be considered an extension of ITU-Tstandard H.264 and ISO/IEC/MPEG 4 part 10 that may enable thetransmission and decoding of partial bit streams to provide videoservices with lower temporal and/or spatial resolutions and/or reducedfidelity while retaining a relatively high reconstruction quality forthe rate of the partial bit streams. A feature of SVC, referred to asSingle Loop Decoding, may refer to an SVC decoder that may set up onemotion compensation loop at the layer being decoded and may not set upone or more motion compensation loop at one or more other lower layers.For example, if a bitstream contains two layers, layer 1 (e.g., a baselayer) and layer 2 (e.g., an enhancement layer), and if a decoder isconfigured to reconstruct layer 2 video, a decoded picture buffer and/ormotion compensated prediction may be set up for layer 2, but not forlayer 1 (e.g., the base layer upon which layer 2 may depend). Withsingle loop decoding, deblocking filtering may also be limited to thelayer being decoded. Thus, SVC may not require a reference picture fromlower layers to be fully reconstructed, which may reduce computationalcomplexity and memory usage at the decoder.

Single loop decoding may be achieved by constrained inter-layer textureprediction, where, for a current block in a given layer, spatial textureprediction from a lower layer may be permitted if the correspondinglower layer block is coded in intra-mode (which may also be referred toas restricted intra-prediction). In an embodiment, this may be due to alower layer block being coded in intra-mode, where such a block may bereconstructed without the need for motion compensation operations and/ora decoded picture buffer.

To further improve rate-distortion efficiency of an enhancement layer,SVC may use additional inter-layer prediction techniques such as motionvector prediction, residual prediction, mode prediction, etc. from lowerlayers. Although a single loop decoding feature of SVC may reduce thecomputational complexity and/or memory usage at a decoder, single loopdecoding may increase implementation complexity by using block-levelinter-layer prediction methods. To compensate for the performancepenalty that may be incurred by imposing the single loop decodingconstraint, encoder design and computation complexity may be increasedsuch that a desired level of performance may be achieved.

Scalable extensions of HEVC may be referred to as SHVC. Standardsscalability for HEVC may refer to the type of scalability that may allowfor the base layer to be encoded with an earlier standard, such asH.264/AVC or MPEG2, while one or more enhancement layers may be encodedusing a more recent standard, such as the HEVC standard. Standardsscalability may provide backward compatibility for legacy content thatmay have been encoded using previous standards. Standards scalabilitymay enhance the quality of such legacy content with one or moreenhancement layers that may be encoded with more current standards likeHEVC that provide better coding efficiency.

FIG. 2 shows example block diagram 200 of an SHVC decoder for a 2-layerscalable system. SHVC may use a high level syntax-based scalable codingframework, where reconstructed pictures from a base layer may beprocessed into inter-layer reference (ILR) pictures. These ILR picturesmay then be inserted into the enhancement layer decoded picture buffer(DPB) for prediction of the enhancement layer pictures. The inter-layerprocessing module in SHVC may include up-sampling for spatialscalability and bit depth scalability and color mapping for color gamutscalability.

As shown in FIG. 2, SHVC bitstream 240 may be demultiplexed intoenhancement layer (EL) stream 241 and base layer (BL) stream 242 bydemultiplexer 210. BL stream 242 may be decoded by base layer decoder231 to generate reconstructed pictures that may be provided to baselayer decoded picture buffer (BL DPB) 232 and that may be provided asbase layer video output 252. BL DPB may provide 262 base layerreconstructed pictures to inter-layer processing 250 that may processsuch base layer reconstructed pictures to generate ILR pictures that maybe provided 261 to enhanced layer decoded picture buffer (EL DPB) 222.HEVC decoder 221 may decode EL stream 241 and provide its reconstructedpictures to EL DPB 222, which may use such HEVC reconstructed picturesand ILR pictures received from inter-layer processing 250 to generateenhancement layer video output 251.

In an embodiment, an Ultra high definition TV (UHDTV) specification maybe used to present images and video using advanced display technologies.Compared to the High Definition TV (HDTV) specification, a UHDTVspecification may support larger spatial resolution, a higherframe-rate, a higher sample bit depth, and/or a wider color gamut. Userexperience may be improved due to the higher fidelity and higher picturequality that UHDTV may provide. UHDTV may support two spatialresolutions, one at 4K (3840×2160) and one at 8K (7680×4320), framerates up to 120 Hz, and/or two bit depths of picture samples at 10 bitsand 12 bits. In addition, the color space of UHDTV may support renderingof a larger volume of visible color information. FIG. 3 shows graph 300illustrating a comparison between HDTV and UHDTV in InternationalCommission on Illumination (CIE) color definition. FIG. 4 shows anexample of the visual difference that may be perceived by an end userbetween the HDTV color gamut and the UHDTV color gamut. In FIG. 4, asame content is color graded twice using different color spaces. FIG. 4Ashows image 410 that may represent an image that may have been colorgraded in HDTV and rendered/displayed on an HDTV display. FIG. 4B showsimage 410 that may represent an image that may have been color graded inUHDTV and rendered/displayed on a HDTV display.

SHVC may support HDTV to UHDTV migration. Efficient coding technologiesdesigned for bit depth scalability and/or color gamut scalability may beincluded into SHVC. Table 1 below lists different types of scalabilitiesthat SHVC may support according to the disclosed embodiments. One ormore of such scalability types may also be supported by the previous SVCstandard.

TABLE 1 SHVC scalability types Scalability Example Standards Spatialscalability 720 p→1080 p SVC, SHVC Quality (SNR) scalability 35 dB→38 dBSVC, SHVC Temporal scalability 30 fps→60 fps SVC, HEVC Standardsscalability H.264/AVC→HEVC SHVC Bit-depth scalability 8-bit video →10-bit video SHVC Color gamut scalability BT.709(HDTV) −> SHVCBT.2020(UHDTV)

A type of scalability may be referred to as color gamut scalability.Color gamut scalable (CGS) coding may be multi-layer coding where two ormore layers may have different color gamuts. For example, as shown inTable 1, in a 2-layer scalable system, a base layer may be an HDTV colorgamut while an enhancement layer may be a UHDTV color gamut. Inter-layerprocessing for CGS coding may use color gamut conversion methods toconvert the base layer color gamut to an enhancement layer color gamut.Inter-layer reference pictures generated by color gamut conversion(e.g., color mapping) methods may be used to predict the enhancementlayer pictures with improved accuracy. Using the pictures shown in FIG.4 as an example, a color gamut conversion process may significantlyreduce and/or alleviate the color differences between the images shownin FIG. 4A and FIG. 4B that may be due to different color grading.Through the use of color gamut conversion methods, the colors in HDTVspace may be translated into the UHDTV space and may be used to predictan enhancement layer signal in the UHDTV space.

FIG. 5 shows block diagram 500 of an exemplary SHVC encoder that maycorrespond to an SHVC decoder such as the exemplary SHVC decoder of FIG.2. Enhancement layer (EL) video 541 may be provided to EL encoder 521that may be an HEVC encoder or a component thereof in an embodiment.Base layer (BL) video 542 may be provided to BL encoder 531 that may bean HEVC encoder or a component thereof in an embodiment. EL video 541may have undergone pre-processing 510 for color grading, downsampling,and/or tone mapping for bit depth conversion to generate BL video 542.EL encoder 521 may provide pictures to EL DPB 522 and BL encoder 531 mayprovide pictures to BL DPB 532.

As shown, exemplary inter-layer (IL) processing module 520 may performcolor gamut conversion from base layer color gamut to enhancement layercolor gamut, upsampling from base layer spatial resolution toenhancement layer spatial resolution, and/or inverse tone mapping fromBL sample bit-depth to EL sample bit-depth. Such processing may beperformed using enhancement layer video information 524 and/or baselayer video information 534 that may have been provided by EL encoder521 and BL encoder 531, respectively. IL processing module 520 may usepicture(s) from BL DPB 532 in its processing and/or may provide data,pictures, or other information to EL DPB 522 for use in predicting ELpictures. Color mapping information 553 generated by IL processingmodule 520 may be provided to multiplexer 540.

Multiplexer 540 may use EL bitstream 551 generated by EL encoder 521 andBL bitstream 552 generated by BL encoder 531 to generate SHVC bitstream550. In an embodiment, multiplexer 540 may also use color mappinginformation 553 to generate SHVC bitstream 550.

Various color gamut conversion methods may be used, including, but notlimited to, linear, piece-wise linear, and polynomial. In the filmindustry and post-production processes, a 3-Dimensional Look-up Table(3D LUT) may be used for color grading and/or color gamut conversionfrom one gamut to another. A 3D LUT-based color gamut conversion processmay be used in SHVC as an inter-layer prediction method for CGS codingas described herein.

An SHVC color mapping process may be based on a 3D LUT. FIG. 6 showsexample 3D LUT based mapping 600 that may be a mapping from 8-bit BLvideo to 8-bit EL video with a range of (0, 0, 0) to (255, 255, 255).Using a 3D color mapping table, 3D LUT 610 may first be split evenly ineach dimension (center cube) into 2×2×2 octants at 620. An SHVC profile(e.g., SHVC Scalable Main 10 profile) may allow at most one split in thethree color dimensions. A luma component may be additionally split into,in some embodiments, at most four parts as shown in 630. A 3D colorspace may be split into up to 8×2×2 cuboid-shaped octants. Within anoctant, a cross color component linear model may be applied to performcolor mapping. For an octant, four vertices may be transmitted torepresent the cross component linear model. The color mapping table maybe transmitted separately for the Y′, Cb, and Cr components. Thus, up to8×2×2×4×3=384 table entries may be stored for CGS coding.

To perform color mapping in SHVC, for a given BL input sample tripletP(y, u, v), located as shown in example cube 700 of FIG. 7, the octantto which it belongs may be determined based on the values of the first Nmost significant bits (MSBs) of the color components (y, u, v) because acolor dimension is partitioned dyadically.

Because luma and the chroma samples may not be phase aligned in thetypical YCbCr 4:2:0 video format, the input P(y, u, v) may be filteredwith 4-tap or 2-tap filters to align the luma and chroma samplelocations.

The linear model for the color component C (C may be Y, U, or V) of theidentified octant may be denoted as lutC[P₀], lutC[P₄], lutC[P₆], andlutC[P₇], which may correspond to the vertices P₀, P₄, P₆, and P₇ asshown in FIG. 7. Accordingly, the output of the color component C of thecolor mapping process may be calculated using equation (1) below, withdy, du, and dv as indicated in FIG. 7. Where there is a spatialresolution difference between the BL and the EL, up-sampling may beapplied after color mapping.

C _(out)=lutC[P ₀]+dy×(lutC[P ₇])−lutC[P ₆])+du×(lutC[P ₄]−lutC[P₀])+dv×(lutC[P ₆]−lutC[P ₄])  (1)

3D LUT parameters may be estimated by an encoder, for example, using aBL signal in one color space and an EL signal in another color space.The Least Square (LS) estimation method may be utilized to estimateoptimal 3D LUT parameters. These model parameters may include the sizeof the 3D LUT (e.g., a number of partitions of the chroma components anda number of partitions of the luma component) and/or linear modelparameters at vertices P₀, P₄, P₆, and P₇ for an octant. In SHVC, theseLUT parameters may be signaled in a bitstream inside a Picture ParameterSet (PPS) such that the decoder may perform the same color gamutconversion process. PPS may carry parameters that are relatively staticand that may not change frequently from picture to picture. PPS updateat a picture level may be used, allowing 3D LUT parameters to besignaled at a sequence level and updated at a picture level. In order toreduce the 3D LUT signaling cost, the model parameters at, e.g., thevertices P₀, P₄, P₆, and P₇ for an octant may be predicted from theirneighboring octants.

The number of bits used to signal model parameters of a 3D LUT may varygreatly based on the size of the 3D LUT. The larger the 3D LUT may be(e.g., the more partitions of the 3D LUT), the more bits it may consume.A larger 3D LUT may provide a finer partition of a color space, such asthat represented by 630 in FIG. 6. The use of a larger 3D LUT may reducedistortion between an original EL signal and a color mapped BL signaland/or may increase the coding efficiency of the EL.

An intelligent encoder may select or determine a 3D LUT size, takinginto consideration a tradeoff between signaling overhead of a 3D LUT andthe 3D LUT's distortion reduction capabilities. For example, a ratedistortion optimization method may be used to select an appropriate 3DLUT size. In an embodiment, a 3D LUT size may be selected by taking intoconsideration (e.g., only) a relative signaling overhead usingpre-selected thresholds. In an embodiment, a 3D LUT size may be reducedwhen the signaling cost of the 3D LUT is over a threshold (e.g., 3%) ofa previously coded picture and increased when its signaling cost isbelow a threshold (e.g., 0.5%) of a previously coded picture.

In an embodiment, an improved 3D LUT size selection method based on ratedistortion cost may be used as set forth herein. By considering the ratedistortion cost of the 3D LUT sizes that may satisfy a maximum sizeconstraint, the disclosed embodiments may determine a 3D LUT size (and,in an embodiment, its associated vertex parameters) that achieves adesired overhead vs. distortion reduction tradeoff A hierarchical Bprediction structure may be taken into account when calculating the ratedistortion cost of 3D LUT tables.

Model parameters associated with P₀, P₄, P₆, and P₇ for an octant may bepredicted using vertex values from a neighboring octant on the left. Fora color component X, with X being Y, U, or V, two predictors, predXa andpredXb, may be calculated. The difference between the actual modelparameters and the associated predictors may be calculated and signaledin the bitstream.

The first predictor predXa may be calculated as the octant coordinateswith, in some embodiments, proper bit shift. Proper bit shift may beused when the input and output of the 3D LUT have different bit depths.For example, when the BL signal is 8-bit and the EL signal is 10-bit, abit shift of 2 may be used. The first predictor may be calculated forP₀, P₄, P₆, and P₇ for all octants. More specifically, predictor predXa,for X being Y, U, or V, may be calculated using equations (2), (3), and(4) shown below.

predYa[yIdx][uIdx][vIdx][vertex]=(vertex<3)?(yIdx<<yShift):((yIdx+1)<<yShift)  (2)

predUa[yIdx][uIdx][vIdx][vertex]=(vertex==0)?(uIdx<<cShift):((uIdx+1)<<cShift)  (3)

predVa[yIdx][uIdx][vIdx][vertex]=(vertex<2)?(vIdx<<cShift):((vIdx+1)<<cShift)  (4)

In equations (2), (3), and (4), yIdx, uIdx, and vIdx may be indices inthe Y, U, and V dimensions that may be used to identify an octant and avertex equal to 0, 1, 2, 3 may indicate the vertices P₀, P₄, P₆, and P₇,respectively.

The second predictor predXb may be calculated as a difference betweenmodel parameters for a left neighboring octant and a first predictorpredA of the left neighboring octant. More specifically, the secondpredictor predXb, for X being Y, U, or V, may be derived as shown in thefollowing example pseudocode section.

if (yIdx > 0) predXb[yIdx][uIdx][vIdx][vertex] = Clip3( − (1 <<(CMOutputBitdepth_(Y/C) − 2)), (1 << (CMOutputBitdepthY/C − 2)),LutX[yIdx − 1][uIdx][vIdx][vertex] − predXa[yIdx −1][uIdx][vIdx][vertex]) else predXb[yIdx][uIdx][vIdx][vertex] = 0

The first predictor predXa and the second predictor predXb may be usedto predict the model parameters of the current octant. The predictionerrors may be calculated by subtracting predXa and predXb from modelparameters of a current octant. Prediction errors may be quantized withcm_res_quant_bits. At the decoder side, model parameters for an octant,which may be denoted as LutX [yIdx][uIdx][vIdx][vertex], with X being Y,U, or V, may be derived using the following equation (5):

LutX[yIdx][uIdx][vIdx][vertex]=(res_x[yIdx][uIdx][vIdx][vertex]<<cm_res_quant_bits)+predXa[yIdx][uIdx][vIdx][vertex]+predXb[yIdx][uIdx][vIdx][vertex]  (5)

where res_x, for x being replaced by Y, U, or V, may be a quantizedprediction error that may be signaled in a bitstream.

Due to quantization of prediction error, using a model parameterprediction method, the derived model parametersLutX[yIdx][uIdx][vIdx][vertex] may have zero bits in thecm_res_quant_bits of the Least Significant Bit (LSB) positions. This mayaffect the precision of the color mapping process. As set forth herein,a vertex prediction method for CGS coding may allow the LSB positions ofthe derived model parameters LutX[yIdx][uIdx][vIdx][vertex] to havenon-zero values and hence improved precision for a color mappingprocess.

In an embodiment, for a given table size s, an associated ratedistortion cost may be calculated using equation (6) as follows:

J _(cost)(s)=D(s)+λ·bits(s)  (6)

where D(s) may be a distortion between an original EL signal and amapped BL signal after color mapping using a 3D LUT with size s applied,bits(s) may be a number of bits used to code the 3D LUT with size s, andλ may be a Lagrange multiplier. The optimal table size may be selectedusing equation (7) as follows:

s ^(opt)=arg min(J _(cost)(s)).  (7)

As video resolution increases, overall distortion (which may becalculated as a sum of distortion of all the pixels in a picture) mayfluctuate more significantly and may overpower the second term λ·bits(s)in equation (6), unless a very large λ is selected. This may result inthe selection of a larger than desired table size more frequently.Another result may be the changing of a selected 3D LUT size morefrequently from picture to picture, which may result in more frequentPPS updates. As set forth herein, the disclosed ILR usage based weighteddistortion calculation may be used.

FIG. 8 illustrates example hierarchical B prediction structure 800 thatmay be used for streaming and broadcasting video applications. Startingfrom a Random Access Point (RAP), depicted in FIG. 8 as picture 0,pictures may be coded out of order (e.g., in an order that is variesfrom a display order) using a hierarchical B prediction structure suchas structure 800. With a Group of Pictures (GOP) of size 8 for each ofGOP 801 and 802 as shown in FIG. 8, every 8 pictures may be groupedtogether and nay be coded out of display order. For example, a codingorder may be applied to GOP 801 such that GOP 801 may include pictures0, 1, 2, 3, 4, 5, 6, 7, and 8 followed by GOP 802 that may includepictures 9, 10, 11, 12, 13, 14, 15, and 16. Within GOP 801, a codingorder of the pictures may be picture 0, picture 8, picture 4, picture 2,picture 1, picture 3, picture 6, picture 5, and picture 7, while withinGOP 802 a coding order of the pictures may be picture 16, picture 12,picture 10, picture 9, picture 11, picture 14, picture 13, and picture15.

The arrows in FIG. 8 show the temporal reference pictures used topredict a picture. For example, picture 0 may be used to predictpictures 1, 2, 3, 4, 8, and 16, while picture 4 may be used to predictpictures 1, 2, 3, 5, 6, 7, and 16, etc. The temporal distance betweenreference pictures and a current picture may vary depending on where thecurrent picture is located within a prediction hierarchy. For example,for picture 8 and picture 16 at the bottom of prediction hierarchy 800,the temporal distance between these pictures and their respectivereference pictures may be large. For example, picture 8 may have as itsreference picture 0. For each of pictures 1, 3, 5, 7 and so on, whichare at the top of exemplary prediction hierarchy 800, the temporaldistance between each of these pictures and their respective referencepictures may be very small. For example, picture 3 may include among itsreferences pictures 2 and 4 that may be temporally adjacent pictures.The temporal distance between a reference picture and a current picturethat the reference picture may be used to predict may affect the usageof the given reference picture. In an embodiment, the closer a referencepicture is to a current picture, the more likely it may be used topredict the current picture. As shown in FIG. 8, the predictionhierarchy may determine how far the temporal reference pictures are froma current picture, and thus may determine the usage of these temporalreference pictures.

FIG. 9 illustrates hierarchical B temporal prediction structure 900 thatmay be extended to a 2-layer scalable video coding system. Inter-layerreference (ILR) pictures may be available for prediction of a currentpicture, for example, as shown by the vertical arrows connectingpictures in base layer 912 to pictures in enhancement layer 911. Forexample, picture 2 in base layer 912, GOP 901 may be connected by avertical arrow to picture 2 in enhancement layer 911, GOP 901,illustrating that picture 2 in base layer 912, GOP 901 may be availablefor prediction of picture 2 in enhancement layer 911, GOP 901.Inter-layer reference pictures and temporal reference pictures may beused for the prediction of the current picture. The usage of aninter-layer reference picture may be directly related to a predictionhierarchy. For example, for low temporal level pictures in enhancementlayer 911 that may not have temporal reference pictures close tothemselves (e.g., picture 8 in enhancement layer 911, GOP 901 ofstructure 900), the usage of ILR pictures may be higher. The usage ofILR pictures for high temporal level pictures in enhancement layer 911(e.g., picture that may have temporally adjacent reference pictures,such as picture 3 in enhancement layer 911, GOP 901 of structure 900)may be lower. Weights based on ILR picture usage may be determined andapplied to distortion term D(s) of equation (6) such that the impact ofchoosing different 3D LUT model parameters may be estimated moreaccurately. That is, the rate distortion cost in equation (6) may bemodified as shown in equation (8):

J _(cost)(s)=w·D(s)+λ·bits(s)  (8)

where w may be a weighting factor based on ILR picture usage. In anembodiment, different weights may be applied depending on a temporallevel of a current picture being coded. Where l may be the temporallevel of the current picture, the weighting factor may be denoted asw(l). In an embodiment, w(l) may be fixed for an entire video sequence.Alternatively, adaptive weights w(l) may be maintained and updateddynamically based on the actual ILR picture usage for pictures intemporal level l.

ILR picture usage may be dependent on the video content being coded. Inan embodiment, dynamic updating of w(l) may allow better contentadaptation. FIG. 10 illustrates example process 1000 of selecting anoptimal size based on rate distortion optimization using weighteddistortion. At 1101, for a current picture in a temporal level l, a costJ(s_(i)) may be calculated for a LUT size s_(i) using equation 9:

J(s _(i))=D(s _(i))*w(l)+λ*r(s _(i))  (9)

where l may represent a temporal level of a current picture, a weightingfactor may be denoted as w(l), D(s_(i)) may be a distortion, λ may be aLagrange multiplier, and r(s_(i)) may be a number of coding bits for aLUT size s_(i).

At 1102, a determination may be made as to whether the cost J(s_(i))determined at 1101 is less than a minimum cost threshold J_(min). If so,at 1103, the minimum cost threshold J_(min) may be set to the costJ(s_(i)) determined at 1101 and the optimal table size s_(opt) may beset to the current table size s_(i). If the cost determined at 1101 isgreater than or equal to a minimum cost threshold J_(min), or afterperforming the functions of 1103 if the cost J(s_(i)) is less thanminimum cost threshold J_(min), the method moves to 1104 where it may bedetermined whether some or all LUT sizes have been tested. If the LUTsizes have not been tested, process 1000 returns to 1101 to performfurther testing.

If the LUT sizes have been tested, at 1105, a color mapping may beapplied to derive an ILR picture using the 3D LUT size s_(opt) as mostrecently determined or set. At 1106 a current picture may be coded usingthe determined information and at 1107 w(l) may be updated based in ILRusage.

Additional considerations may be used when determining an optimal 3D LUTsize to improve performance and/or to reduce encoder complexity. In anembodiment, ILR usage w(l) may also be tracked for a picture or a slicetype at a temporal level. For example, a weighting factor may be trackedas w(l, t), where l may be the temporal level and t may be thepicture/slice type (e.g., t may be I_SLICE, P_SLICE, or B_SLICE).Because coded EL pictures may also be used to encode other future ELpictures in coding order, rate distortion based 3D LUT parameterselection may also depend on an impact of a current picture for codingof future EL pictures. For example, for non-reference pictures in an EL,picture level updates of 3D LUT may be disabled because of increasedquality of non-reference EL pictures (e.g., due to more accurate colormapping) may not benefit any other pictures. Picture level 3D LUTupdates may be disabled for pictures at a temporal level above a certainthreshold. For example, picture level 3D LUT updates may be disabled forthe pictures in the two highest temporal levels. For example, in FIG. 9,picture level 3D LUT updates may not be applied to any odd numberedpictures or pictures 2, 6, 10, and 14.

In HEVC, following a, or each, Clean Random Access (CRA) picture, theremay be pictures that are earlier in display order and later in codingorder, and that may not be decodable if pictures in the previous RandomAccess Period are discarded. This may occur, for example, when a userswitches channels. These pictures may be referred to as the RandomAccess Skipped Leading (RASL) pictures in HEVC. In an embodiment,picture level 3D LUT update may be disabled for RASL pictures.

In an embodiment, given a maximum 3D LUT size, some or all 3D LUT sizesthat are smaller than the maximum size may not be considered. Forexample, the number of bits used to code each picture (e.g., for eachpicture type at each temporal level) and the number of bits used to code3D LUT (e.g., for each 3D LUT size smaller than the maximum) may betracked. If a given 3D LUT size is expected to generate a signalingoverhead larger than a certain percentage threshold (for example, 25%)of the number of bits expected to code the current picture, then this 3DLUT size may be excluded from the rate distortion decision of process1000 in FIG. 10.

Referring again to FIG. 7, vertex positions of an octant may be labeledfrom P₀ to P₇. Some vertices may be shared between neighboring octants.For example, the vertex position P₀ of a current octant may be at thesame position as P₁ in a left neighboring octant, the vertex position P₄of a current octant may be at a same position as P₅ in a leftneighboring octant, and so on. Consider vertex position P₀ of a currentoctant as shown in FIG. 7, for example. Using model parameters receivedfor a left neighboring octant, parameter values of the vertex positionof P₁ of the left neighboring octant may be derived. For example, forcolor component X, with X being Y, U, or V, the following examplepseudocode section may be used to derive the value of P₁ of the leftneighboring octant. (yIdx, uIdx, vIdx) as shown in the section below maybe an index of a current octant to be coded.

deltaY = octantLengthY deltaU = 0 deltaV = 0 valueXP1 =LutX[yIdx−1][uIdx][vIdx][0] + ((((deltaY * (LutX[yIdx− 1][uIdx][vIdx][3]− LutX[yIdx − 1][uIdx][vIdx][2])) << cShift2Idx) + ((deltaU *(LutX[yIdx−1][uIdx][vIdx][1] − LutX[yIdx − 1][uIdx][vIdx][0])) <<yShift2Idx) + ((deltaV * (LutX[yIdx− 1][uIdx][vIdx][2] − LutX[yIdx −1][uIdx][vIdx][1])) << yShift2Idx) + nMappingOffset) >> nMappingShift)

This derived value valueXP1 may be used as a predictor for the vertex P₀of the current octant. The prediction error may be calculated using thispredictor valueXP1. The prediction error may be quantized using thefactor cm_res_quant_bits. At a decoder, the model parameter for P₀ ofthe current octant may be calculated by adding valueXP1 to thede-quantized prediction error, as shown in the following equation (10):

LutX[yIdx][uIdx][vIdx][0]=(res[yIdx][uIdx][vIdx][vertex]<<cm_res_quant_bits)+valueXP1  (10)

Although the quantized prediction error may have zero values incm_res_quant_bits LSB positions, the predictor valueXP1 may not.Therefore, derived model parameters for a vertex position P₀ of acurrent octant, LutX[yIdx][uIdx][vIdx][0], may have improved precision.

Although the embodiments set forth herein may be discussed using vertexP₀ of a current octant as an example, predictors for remaining verticesP₄ and P₆ may be derived in a similar manner. For a vertex position P₇,external interpolation instead of internal interpolation may be usedbecause P₇ may not be a shared vertex with a left neighboring octant.However, external interpolation may not produce good quality predictionsbecause a 3D LUT may be trained based on internal interpolation (e.g.,only on internal interpolation). In an embodiment, prediction of modelparameters for P₇ may be calculated from vertex P₆ of a current octant.The correlation between Y and U may be weaker than the correlationbetween Y and V for UHDTV color space. Therefore, a luma componentdifference between P₇ and P₆ in its neighboring octant with octant index(yIdx, uIdx−1, vIdx) may be derived. This derivation process may beperformed as shown below in the following example sections ofpseudocode.

If uIdx is greater than 0, then valueXP7 may be calculated as:

valueYP7 = LutY[yIdx][uIdx][vIdx][2] + (LutY[yIdx][uIdx−1][vIdx][3] −LutY[yIdx][uIdx−1][vIdx][2]) valueUP7 = LutU[yIdx][uIdx][vIdx][2]valueVP7 = LutV[yIdx][uIdx][vIdx][2] .

Otherwise, valueXP7 may be calculated as:

valueYP7 = LutY[yIdx][uIdx][vIdx][2] + (octantLengthY<<(CMOutputBitdepthC− CMInputBitdepthC)) valueUP7 =LutU[yIdx][uIdx][vIdx][2] valueVP7 = LutV[yIdx][uIdx][vIdx][2] .

In an embodiment, instead of using a left neighboring octant (e.g., anoctant with octant index (yIdx−1, uIdx, uIdx)) to predict modelparameters for a current octant, other neighboring octants may be used.For example, the octants with octant index (yIdx, uIdx−1, vIdx), (yIdx,uIdx, vIdx−1), (yIdx−1, uIdx−1, vIdx), (yIdx−1, uIdx, vIdx−1), (yIdx,uIdx−1, vIdx−1), and/or (yIdx−1, uIdx−1, vIdx−1) may be used. Thepredictors may also be calculated by combining two or more predictorsfrom these neighboring octants to further improve precision.

In an embodiment, an entropy coding method for 3D LUT parameters may beimplemented as described herein. A prediction residual value may bedenoted as resCoeff. resCoeff may be coded by Exp-Golomb coding of theMSB of the absolute value of resCoeff, 7-bit fixed-length coding of theremaining LSB of the absolute value of resCoeff, and setting a one bitflag for the sign if the absolute value of resCoeff is non-zero. Morespecifically, Table 2 below is a syntax table followed by semantics thatmay be used in an embodiment, in which res_coeff_q may represent theMSB, res_coeff_r may represent the LSB, and res_coeff_s may representthe sign.

TABLE 2 Entropy Coding Syntax Table Descriptor color_mapping_octants(depth, yIdx, uIdx, vIdx, length ) { [Ed. (MH): Camel casing suggestedfor all input parameters, i.e. depth and length should be changed.] if (depth < cm_octant_depth ) split_octant_flag u(1) if ( split_octant_flag) for( k = 0; k < 2; k++ ) for( m = 0; m < 2 ; m++ ) for( n = 0; n < 2;n++ ) color_mapping_octants( depth + 1, yIdx + YPartNum * k * length /2, uIdx + m * length / 2, vIdx + n * length / 2, length / 2) else for( i= 0; i < YPartNum; i++ ) for( j = 0; j < 4; j++ ) { coded_res_flag[yIdx + (i << (cm_octant_depth-depth)) ][ uIdx ][ vIdx ][ j ] u(1) if(coded_res_flag[ yIdx + (i << (cm_octant_depth-depth)) ][ uIdx ][ vIdx ][j ] ) for( c = 0; c < 3; c++ ) { res_coeff_q[ yIdx + (i <<(cm_octant_depth-depth)) ][ uIdx ][ vIdx ][ j ][ c ] ) ue(v)res_coeff_r[ yIdx + (i << (cm_octant_depth-depth)) ][ uIdx ][ vIdx ][ j][ c ] ) u(7) if( res_coeff_q[ yIdx + (i << (cm_octant_depth- depth)) ][uIdx ][ vIdx ][ j ][ c ] | | res_coeff_r[ yIdx + (i << (cm_octant_depth-depth)) ][ uIdx ][ vIdx ][ j ][ c ]) res_coeff_s[ yIdx + (i <<(cm_octant_depth- u(1) depth)) ][ uIdx ][ vIdx ][ j ][ c ] ) } } }

In Table 2, res_coeff_q[yIdx][uIdx][vIdx][i][c] may specify a quotientof a residual for a color mapping coefficient with index[yIdx][uIdx][vIdx][i][c]. When not present, the value of res_coeff_q maybe inferred to be equal to 0.

In Table 2, res_coeff_r[yIdx][uIdx][vIdx][i][c] may specify a remainderof a residual for a color mapping coefficient with index[yIdx][uIdx][vIdx][i][c]. When not present, the value of res_coeff_q maybe inferred to be equal to 0.

In Table 2, res_coeff_s [yIdx][uIdx][vIdx][pIdx][cIdx] may specify asign of a residual for a color mapping coefficient with index[yIdx][uIdx][vIdx][i][c]. When not present, the value of res_coeff_s maybe inferred to be equal to 0.

In order to reconstruct the value of resCoeff, res_coeff_q, res_coeff_r,and res_coeff_s may be assembled together. More specifically, thefollowing decoding process may be used to reconstruct a predictionresidual for a color component, a parameter, and an octant.

The variables CMResY[yIdx][uIdx][vIdx][i], CMResU[yIdx][uIdx][vIdx][i]and CMResV[yIdx][uIdx][vIdx][i] may be derived using equations 11, 12,and 13, respectively, as follows:

CMResY[yIdx][uIdx][vIdx][i]=(1−2*res_coeff_s[yIdx][uIdx][vIdx][i][0])*((res_coeff_q[yIdx][uIdx][vIdx][i][0]<<7)+res_coeff_r[yIdx][uIdx][vIdx][i][0])  (11)

CMResU[yIdx][uIdx][vIdx][i]=(1−2*res_coeff_s[yIdx][uIdx][vIdx][i][1])*((res_coeff_q[yIdx][uIdx][vIdx][i][1]<<7)+res_coeff_r[yIdx][uIdx][vIdx][i][1])  (12)

CMResV[yIdx][uIdx][vIdx][i]=(1−2*res_coeff_s[yIdx][uIdx][vIdx][i][2])*((res_coeff_q[yIdx][uIdx][vIdx][i][2]<<7)+res_coeff_r[yIdx][uIdx][vIdx][i][2])  (13)

A number of LSBs may be fixed to be 7. Alternatively, a different numberof LSBs may be used. For example, a different number of LSBs may be usedwhere a fixed value of 7 to divide the magnitude (e.g., absolute) valueof a prediction residual resCoeff into two parts is not desired. Amagnitude of resCoeff may have two parts, an integer part and a decimalpart, but the point at which these two parts are divided may not befixed and may depend on one or both of two factors in a CGS system, avalue of cm_res_quant_bits for a current 3D LUT and a value ofnMappingShift that may depend on a delta between an input bit depth andan output bit depth. In an embodiment, nMappingShift may be equal to 10minus the difference between outputDepth and inputDepth.

In an embodiment, a total number of bits used to represent a magnitudeof resCoeff may be denoted as N. A decimal part of resCoeff magnitudemay be represented in (nMappingShift-cm_res_quant_bits) number of bitsand an integer part of resCoeff magnitude may be represented by aremaining (N-nMappingShift+cm_res_quant_bits) number of bits.

In an embodiment, a length of LSBs that may be fixed-length coded may beadaptively chosen. A value of(nMappingShift-cm_res_quant_bits-cm_delta_flc_bits) may be used todetermine a number of LSBs that may be fixed-length coded, wherecm_delta_flc_bits may be a relatively small integer value such as 0, 1,2, or 3. A value of cm_delta_flc_bits may be preselected by anencoder/decoder and may be fixed. A value of cm_delta_flc_bits may beadaptively selected by an encoder and signaled as part of a 3D LUT tableusing the following syntax table Table 3 and semantics. In order todetermine cm_delta_flc_bits, an encoder may count a number of bitsneeded to code some or all resCoeff values for some or all colorcomponents, some or all model parameters, and some or all octants, foran allowed value of cm_delta_flc_bits (e.g., 0 to 3). The encoder mayselect a cm_delta_flc_bits value that minimizes an overall cost ofcoding all resCoeff values. The complexity of such an exhaustive searchmay be very small when only numbers of bits are counted, and actualcoding may not be performed.

TABLE 3 Syntax Table Descriptor color_mapping_table( ) { cm_octant_depthu(2) cm_y_part_num_log2 u(2) cm_input_luma_bit_depth_minus8 u(3)cm_input_chroma_bit_depth_delta se(v) cm_output_luma_bit_depth_minus8u(3) cm_output_chroma_bit_depth_delta se(v) cm_res_quant_bits u(2)cm_delta_flc_bits u(2) if( cm_octant_depth = = 1 ) {cm_adapt_threshold_u_delta se(v) cm_adapt_threshold_v_delta se(v) }color_mapping_octants( 0, 0, 0, 0, 1 << cm_octant_depth ) }

In an embodiment, cm_res_quant_bits may specify a number of leastsignificant bits to be added to a vertex residual values res_y, res_uand res_v. A reconstruction of a prediction residual for each colorcomponent, each parameter, and each octant may be revised as describedherein. The variables CMResY[yIdx][uIdx][vIdx][i],CMResU[yIdx][uIdx][vIdx][i], and CMResV[yIdx][uIdx][vIdx][i] may bederived as shown below in equations 14, 15, 16, and 17:

nFLCBits=nMappingShift−res_quant_bits−cm_delta_flc_bits  (14)

CMResY[yIdx][uIdx][vIdx][i]=(1−2*res_coeff_s[yIdx][uIdx][vIdx][i][0])*((res_coeff_q[yIdx][uIdx][vIdx][i][0]<<nFLCBits)+res_coeff_r[yIdx][uIdx][vIdx][i][0])  (15)

CMResU[yIdx][uIdx][vIdx][i]=(1−2*res_coeff_s[yIdx][uIdx][vIdx][i][1])*((res_coeff_q[yIdx][uIdx][vIdx][i][1]<<nFLCBits)+res_coeff_r[yIdx][uIdx][vIdx][i][1])  (16)

CMResV[yIdx][uIdx][vIdx][i]=(1−2*res_coeff_s[yIdx][uIdx][vIdx][i][2])*((res_coeff_q[yIdx][uIdx][vIdx][i][2]<<nFLCBits)+res_coeff_r[yIdx][uIdx][vIdx][i][2])  (17)

FIG. 11A is a diagram of an example communications system 100 in whichone or more disclosed embodiments may be implemented. The communicationssystem 100 may be a multiple access system that provides content, suchas voice, data, video, messaging, broadcast, etc., to multiple wirelessusers. The communications system 100 may enable multiple wireless usersto access such content through the sharing of system resources,including wireless bandwidth. For example, the communications systems100 may employ one or more channel access methods, such as code divisionmultiple access (CDMA), time division multiple access (TDMA), frequencydivision multiple access (FDMA), orthogonal FDMA (OFDMA), single carrierFDMA (SC-FDMA), and the like.

FIG. 11A is a diagram of an example communications system 100 in whichone or more disclosed embodiments may be implemented. The communicationssystem 100 may be a multiple access system that provides content, suchas voice, data, video, messaging, broadcast, etc., to multiple wirelessusers. The communications system 100 may enable multiple wireless usersto access such content through the sharing of system resources,including wireless bandwidth. For example, the communications systems100 may employ one or more channel access methods, such as code divisionmultiple access (CDMA), time division multiple access (TDMA), frequencydivision multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrierFDMA (SC-FDMA), and the like.

As shown in FIG. 11A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102 a, 102 b, 102 c, and/or 102 d (whichgenerally or collectively may be referred to as WTRU 102), a radioaccess network (RAN) 103/104/105, a core network 106/107/109, a publicswitched telephone network (PSTN) 108, the Internet 110, and othernetworks 112, though it will be appreciated that the disclosedembodiments contemplate any number of WTRUs, base stations, networks,and/or network elements. Each of the WTRUs 102 a, 102 b, 102 c, 102 dmay be any type of device configured to operate and/or communicate in awireless environment. By way of example, the WTRUs 102 a, 102 b, 102 c,102 d may be configured to transmit and/or receive wireless signals andmay include user equipment (UE), a mobile station, a fixed or mobilesubscriber unit, a pager, a cellular telephone, a personal digitalassistant (PDA), a smartphone, a laptop, a netbook, a personal computer,a wireless sensor, consumer electronics, and the like.

The communications systems 100 may also include a base station 114 a anda base station 114 b. Each of the base stations 114 a, 114 b may be anytype of device configured to wirelessly interface with at least one ofthe WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to one or morecommunication networks, such as the core network 106/107/109, theInternet 110, and/or the networks 112. By way of example, the basestations 114 a, 114 b may be a base transceiver station (BTS), a Node-B,an eNode B, a Home Node B, a Home eNode B, a site controller, an accesspoint (AP), a wireless router, and the like. While the base stations 114a, 114 b are each depicted as a single element, it will be appreciatedthat the base stations 114 a, 114 b may include any number ofinterconnected base stations and/or network elements.

The base station 114 a may be part of the RAN 103/104/105, which mayalso include other base stations and/or network elements (not shown),such as a base station controller (BSC), a radio network controller(RNC), relay nodes, etc. The base station 114 a and/or the base station114 b may be configured to transmit and/or receive wireless signalswithin a particular geographic region, which may be referred to as acell (not shown). The cell may further be divided into cell sectors. Forexample, the cell associated with the base station 114 a may be dividedinto three sectors. Thus, in one embodiment, the base station 114 a mayinclude three transceivers, e.g., one for each sector of the cell. Inanother embodiment, the base station 114 a may employ multiple-inputmultiple output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 115/116/117,which may be any suitable wireless communication link (e.g., radiofrequency (RF), microwave, infrared (IR), ultraviolet (UV), visiblelight, etc.). The air interface 115/116/117 may be established using anysuitable radio access technology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 103/104/105 and the WTRUs 102a, 102 b, 102 c may implement a radio technology such as UniversalMobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA),which may establish the air interface 115/116/117 using wideband CDMA(WCDMA). WCDMA may include communication protocols such as High-SpeedPacket Access (HSPA) and/or Evolved HSPA (HSPA+). HSPA may includeHigh-Speed Downlink Packet Access (HSDPA) and/or High-Speed UplinkPacket Access (HSUPA).

In another embodiment, the base station 114 a and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Evolved UMTSTerrestrial Radio Access (E-UTRA), which may establish the air interface115/116/117 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.16 (e.g.,Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,CDMA2000 1×, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), InterimStandard 95 (IS-95), Interim Standard 856 (IS-856), Global System forMobile communications (GSM), Enhanced Data rates for GSM Evolution(EDGE), GSM EDGE (GERAN), and the like.

The base station 114 b in FIG. 11A may be a wireless router, Home NodeB, Home eNode B, or access point, for example, and may utilize anysuitable RAT for facilitating wireless connectivity in a localized area,such as a place of business, a home, a vehicle, a campus, and the like.In one embodiment, the base station 114 b and the WTRUs 102 c, 102 d mayimplement a radio technology such as IEEE 802.11 to establish a wirelesslocal area network (WLAN). In another embodiment, the base station 114 band the WTRUs 102 c, 102 d may implement a radio technology such as IEEE802.15 to establish a wireless personal area network (WPAN). In yetanother embodiment, the base station 114 b and the WTRUs 102 c, 102 dmay utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, etc.) to establish a picocell or femtocell. As shown in FIG. 11A,the base station 114 b may have a direct connection to the Internet 110.Thus, the base station 114 b may not be required to access the Internet110 via the core network 106/107/109.

The RAN 103/104/105 may be in communication with the core network106/107/109, which may be any type of network configured to providevoice, data, applications, and/or voice over internet protocol (VoIP)services to one or more of the WTRUs 102 a, 102 b, 102 c, 102 d. Forexample, the core network 106/107/109 may provide call control, billingservices, mobile location-based services, pre-paid calling, Internetconnectivity, video distribution, etc., and/or perform high-levelsecurity functions, such as user authentication. Although not shown inFIG. 1A, it will be appreciated that the RAN 103/104/105 and/or the corenetwork 106/107/109 may be in direct or indirect communication withother RANs that employ the same RAT as the RAN 103/104/105 or adifferent RAT. For example, in addition to being connected to the RAN103/104/105, which may be utilizing an E-UTRA radio technology, the corenetwork 106/107/109 may also be in communication with another RAN (notshown) employing a GSM radio technology.

The core network 106/107/109 may also serve as a gateway for the WTRUs102 a, 102 b, 102 c, 102 d to access the PSTN 108, the Internet 110,and/or other networks 112. The PSTN 108 may include circuit-switchedtelephone networks that provide plain old telephone service (POTS). TheInternet 110 may include a global system of interconnected computernetworks and devices that use common communication protocols, such asthe transmission control protocol (TCP), user datagram protocol (UDP)and the internet protocol (IP) in the TCP/IP internet protocol suite.The networks 112 may include wired or wireless communications networksowned and/or operated by other service providers. For example, thenetworks 112 may include another core network connected to one or moreRANs, which may employ the same RAT as the RAN 103/104/105 or adifferent RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities, e.g., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks. For example, the WTRU 102 c shown in FIG. 11A may be configuredto communicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 11B is a system diagram of an example WTRU 102. As shown in FIG.11B, the WTRU 102 may include a processor 118, a transceiver 120, atransmit/receive element 122, a speaker/microphone 124, a keypad 126, adisplay/touchpad 128, non-removable memory 130, removable memory 132, apower source 134, a global positioning system (GPS) chipset 136, andother peripherals 138. It will be appreciated that the WTRU 102 mayinclude any sub-combination of the foregoing elements while remainingconsistent with an embodiment. Also, embodiments contemplate that thebase stations 114 a and 114 b, and/or the nodes that base stations 114 aand 114 b may represent, such as but not limited to transceiver station(BTS), a Node-B, a site controller, an access point (AP), a home node-B,an evolved home node-B (eNodeB), a home evolved node-B (HeNB), a homeevolved node-B gateway, and proxy nodes, among others, may include someor all of the elements depicted in FIG. 11B and described herein.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 11Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 115/116/117. For example, in one embodiment,the transmit/receive element 122 may be an antenna configured totransmit and/or receive RF signals. In another embodiment, thetransmit/receive element 122 may be an emitter/detector configured totransmit and/or receive IR, UV, or visible light signals, for example.In yet another embodiment, the transmit/receive element 122 may beconfigured to transmit and receive both RF and light signals. It will beappreciated that the transmit/receive element 122 may be configured totransmit and/or receive any combination of wireless signals.

In addition, although the transmit/receive element 122 is depicted inFIG. 11B as a single element, the WTRU 102 may include any number oftransmit/receive elements 122. More specifically, the WTRU 102 mayemploy MIMO technology. Thus, in one embodiment, the WTRU 102 mayinclude two or more transmit/receive elements 122 (e.g., multipleantennas) for transmitting and receiving wireless signals over the airinterface 115/116/117.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 130 and/or the removable memory 132.The non-removable memory 130 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 115/116/117from a base station (e.g., base stations 114 a, 114 b) and/or determineits location based on the timing of the signals being received from twoor more nearby base stations. It will be appreciated that the WTRU 102may acquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality, and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

FIG. 11C is a system diagram of the RAN 103 and the core network 106according to an embodiment. As noted above, the RAN 103 may employ aUTRA radio technology to communicate with the WTRUs 102 a, 102 b, 102 cover the air interface 115. The RAN 103 may also be in communicationwith the core network 106. As shown in FIG. 11C, the RAN 103 may includeNode-Bs 140 a, 140 b, 140 c, which may each include one or moretransceivers for communicating with the WTRUs 102 a, 102 b, 102 c overthe air interface 115. The Node-Bs 140 a, 140 b, 140 c may each beassociated with a particular cell (not shown) within the RAN 103. TheRAN 103 may also include RNCs 142 a, 142 b. It will be appreciated thatthe RAN 103 may include any number of Node-Bs and RNCs while remainingconsistent with an embodiment.

As shown in FIG. 11C, the Node-Bs 140 a, 140 b may be in communicationwith the RNC 142 a. Additionally, the Node-B 140 c may be incommunication with the RNC 142 b. The Node-Bs 140 a, 140 b, 140 c maycommunicate with the respective RNCs 142 a, 142 b via an Iub interface.The RNCs 142 a, 142 b may be in communication with one another via anIur interface. Each of the RNCs 142 a, 142 b may be configured tocontrol the respective Node-Bs 140 a, 140 b, 140 c to which it isconnected. In addition, each of the RNCs 142 a, 142 b may be configuredto carry out or support other functionality, such as outer loop powercontrol, load control, admission control, packet scheduling, handovercontrol, macrodiversity, security functions, data encryption, and thelike.

The core network 106 shown in FIG. 11C may include a media gateway (MGW)144, a mobile switching center (MSC) 146, a serving GPRS support node(SGSN) 148, and/or a gateway GPRS support node (GGSN) 150. While each ofthe foregoing elements are depicted as part of the core network 106, itwill be appreciated that any one of these elements may be owned and/oroperated by an entity other than the core network operator.

The RNC 142 a in the RAN 103 may be connected to the MSC 146 in the corenetwork 106 via an IuCS interface. The MSC 146 may be connected to theMGW 144. The MSC 146 and the MGW 144 may provide the WTRUs 102 a, 102 b,102 c with access to circuit-switched networks, such as the PSTN 108, tofacilitate communications between the WTRUs 102 a, 102 b, 102 c andtraditional land-line communications devices.

The RNC 142 a in the RAN 103 may also be connected to the SGSN 148 inthe core network 106 via an IuPS interface. The SGSN 148 may beconnected to the GGSN 150. The SGSN 148 and the GGSN 150 may provide theWTRUs 102 a, 102 b, 102 c with access to packet-switched networks, suchas the Internet 110, to facilitate communications between and the WTRUs102 a, 102 b, 102 c and IP-enabled devices.

As noted above, the core network 106 may also be connected to thenetworks 112, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

FIG. 11D is a system diagram of the RAN 104 and the core network 107according to an embodiment. As noted above, the RAN 104 may employ anE-UTRA radio technology to communicate with the WTRUs 102 a, 102 b, 102c over the air interface 116. The RAN 104 may also be in communicationwith the core network 107.

The RAN 104 may include eNode-Bs 160 a, 160 b, 160 c, though it will beappreciated that the RAN 104 may include any number of eNode-Bs whileremaining consistent with an embodiment. The eNode-Bs 160 a, 160 b, 160c may each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the eNode-Bs 160 a, 160 b, 160 c may implement MIMO technology. Thus,the eNode-B 160 a, for example, may use multiple antennas to transmitwireless signals to, and receive wireless signals from, the WTRU 102 a.

Each of the eNode-Bs 160 a, 160 b, 160 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the uplink and/or downlink, and the like. As shown in FIG. 11D, theeNode-Bs 160 a, 160 b, 160 c may communicate with one another over an X2interface.

The core network 107 shown in FIG. 11D may include a mobility managementgateway (MME) 162, a serving gateway 164, and a packet data network(PDN) gateway 166. While each of the foregoing elements are depicted aspart of the core network 107, it will be appreciated that any one ofthese elements may be owned and/or operated by an entity other than thecore network operator.

The MME 162 may be connected to each of the eNode-Bs 160 a, 160 b, 160 cin the RAN 104 via an S1 interface and may serve as a control node. Forexample, the MME 162 may be responsible for authenticating users of theWTRUs 102 a, 102 b, 102 c, bearer activation/deactivation, selecting aparticular serving gateway during an initial attach of the WTRUs 102 a,102 b, 102 c, and the like. The MME 162 may also provide a control planefunction for switching between the RAN 104 and other RANs (not shown)that employ other radio technologies, such as GSM or WCDMA.

The serving gateway 164 may be connected to each of the eNode-Bs 160 a,160 b, 160 c in the RAN 104 via the S1 interface. The serving gateway164 may generally route and forward user data packets to/from the WTRUs102 a, 102 b, 102 c. The serving gateway 164 may also perform otherfunctions, such as anchoring user planes during inter-eNode B handovers,triggering paging when downlink data is available for the WTRUs 102 a,102 b, 102 c, managing and storing contexts of the WTRUs 102 a, 102 b,102 c, and the like.

The serving gateway 164 may also be connected to the PDN gateway 166,which may provide the WTRUs 102 a, 102 b, 102 c with access topacket-switched networks, such as the Internet 110, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and IP-enableddevices.

The core network 107 may facilitate communications with other networks.For example, the core network 107 may provide the WTRUs 102 a, 102 b,102 c with access to circuit-switched networks, such as the PSTN 108, tofacilitate communications between the WTRUs 102 a, 102 b, 102 c andtraditional land-line communications devices. For example, the corenetwork 107 may include, or may communicate with, an IP gateway (e.g.,an IP multimedia subsystem (IMS) server) that serves as an interfacebetween the core network 107 and the PSTN 108. In addition, the corenetwork 107 may provide the WTRUs 102 a, 102 b, 102 c with access to thenetworks 112, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

FIG. 11E is a system diagram of the RAN 105 and the core network 109according to an embodiment. The RAN 105 may be an access service network(ASN) that employs IEEE 802.16 radio technology to communicate with theWTRUs 102 a, 102 b, 102 c over the air interface 117. As will be furtherdiscussed below, the communication links between the differentfunctional entities of the WTRUs 102 a, 102 b, 102 c, the RAN 105, andthe core network 109 may be defined as reference points.

As shown in FIG. 11E, the RAN 105 may include base stations 180 a, 180b, 180 c, and an ASN gateway 182, though it will be appreciated that theRAN 105 may include any number of base stations and ASN gateways whileremaining consistent with an embodiment. The base stations 180 a, 180 b,180 c may each be associated with a particular cell (not shown) in theRAN 105 and may each include one or more transceivers for communicatingwith the WTRUs 102 a, 102 b, 102 c over the air interface 117. In oneembodiment, the base stations 180 a, 180 b, 180 c may implement MIMOtechnology. Thus, the base station 180 a, for example, may use multipleantennas to transmit wireless signals to, and receive wireless signalsfrom, the WTRU 102 a. The base stations 180 a, 180 b, 180 c may alsoprovide mobility management functions, such as handoff triggering,tunnel establishment, radio resource management, traffic classification,quality of service (QoS) policy enforcement, and the like. The ASNgateway 182 may serve as a traffic aggregation point and may beresponsible for paging, caching of subscriber profiles, routing to thecore network 109, and the like.

The air interface 117 between the WTRUs 102 a, 102 b, 102 c and the RAN105 may be defined as an R1 reference point that implements the IEEE802.16 specification. In addition, each of the WTRUs 102 a, 102 b, 102 cmay establish a logical interface (not shown) with the core network 109.The logical interface between the WTRUs 102 a, 102 b, 102 c and the corenetwork 109 may be defined as an R2 reference point, which may be usedfor authentication, authorization, IP host configuration management,and/or mobility management.

The communication link between each of the base stations 180 a, 180 b,180 c may be defined as an R8 reference point that includes protocolsfor facilitating WTRU handovers and the transfer of data between basestations. The communication link between the base stations 180 a, 180 b,180 c and the ASN gateway 182 may be defined as an R6 reference point.The R6 reference point may include protocols for facilitating mobilitymanagement based on mobility events associated with each of the WTRUs102 a, 102 b, 102 c.

As shown in FIG. 11E, the RAN 105 may be connected to the core network109. The communication link between the RAN 105 and the core network 109may defined as an R3 reference point that includes protocols forfacilitating data transfer and mobility management capabilities, forexample. The core network 109 may include a mobile IP home agent(MIP-HA) 184, an authentication, authorization, accounting (AAA) server186, and a gateway 188. While each of the foregoing elements aredepicted as part of the core network 109, it will be appreciated thatany one of these elements may be owned and/or operated by an entityother than the core network operator.

The MIP-HA may be responsible for IP address management, and may enablethe WTRUs 102 a, 102 b, 102 c to roam between different ASNs and/ordifferent core networks. The MIP-HA 184 may provide the WTRUs 102 a, 102b, 102 c with access to packet-switched networks, such as the Internet110, to facilitate communications between the WTRUs 102 a, 102 b, 102 cand IP-enabled devices. The AAA server 186 may be responsible for userauthentication and for supporting user services. The gateway 188 mayfacilitate interworking with other networks. For example, the gateway188 may provide the WTRUs 102 a, 102 b, 102 c with access tocircuit-switched networks, such as the PSTN 108, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and traditionalland-line communications devices. In addition, the gateway 188 mayprovide the WTRUs 102 a, 102 b, 102 c with access to the networks 112,which may include other wired or wireless networks that are owned and/oroperated by other service providers.

Although not shown in FIG. 11E, it will be appreciated that the RAN 105may be connected to other ASNs and the core network 109 may be connectedto other core networks. The communication link between the RAN 105 theother ASNs may be defined as an R4 reference point, which may includeprotocols for coordinating the mobility of the WTRUs 102 a, 102 b, 102 cbetween the RAN 105 and the other ASNs. The communication link betweenthe core network 109 and the other core networks may be defined as an R5reference, which may include protocols for facilitating interworkingbetween home core networks and visited core networks.

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, UE, terminal, base station, RNC, or any host computer.

1-22. (canceled)
 23. A method for coding video content, the methodcomprising: receiving a current picture of a video; determining alook-up table (LUT) size of a color mapping LUT for the current picturebased on a potential rate-distortion cost; generating the color mappingLUT of the determined LUT size for the current picture; deriving, usingthe color mapping LUT of the LUT size, an inter-layer reference (ILR)picture based on the current picture; and including an indication of thedetermined LUT size for the color mapping LUT associated with thecurrent picture in a bitstream.
 24. The method of claim 23, wherein theLUT size for the color mapping LUT associated with the current pictureis selected from a plurality of potential LUT sizes, and the methodfurther comprises: calculating a plurality of potential rate-distortioncosts that correspond to coding the current picture with the pluralityof potential LUT sizes; and selecting an optimal LUT size thatcorresponds to the smallest rate-distortion cost as the LUT size for thecolor mapping LUT associated with the current picture.
 25. The method ofclaim 24, wherein the plurality of potential LUT sizes are limited by amaximum LUT size, and the method further comprises: estimating a numberof bits for coding the current picture; and determining the maximum LUTsize based on the estimated number of bits for coding the currentpicture.
 26. The method of claim 23, further comprising: identifying atemporal level of the current picture; and calculating the potentialrate-distortion cost based on the identified temporal level of thecurrent picture, wherein distortion is weighted more heavily for a lowertemporal level than a higher temporal level.
 27. The method of claim 23,further comprising: identifying a temporal level of the current picture;determining a distortion weighting factor based on the temporal level ofthe current picture; and calculating the potential rate-distortion costusing the distortion weighting factor such that distortion is weightedmore heavily when the temporal level of the current picture is a lowtemporal level than when the temporal level of the current picture is ahigh temporal level.
 28. The method of claim 23, further comprising:generating an enhancement layer picture based on the current picture;determining a usage of the ILR picture in predicting the enhancementlayer picture; and determining, based on the determined usage of the ILRpicture, a distortion weighting factor for calculating the potentialrate-distortion cost such that distortion is weighted more heavily whenthe ILR picture is used in predicting the enhancement layer picture. 29.The method of claim 23, further comprising: calculating a firstrate-distortion cost associated of coding the current picture using acolor mapping LUT of a first LUT size; and calculating a secondrate-distortion cost associated of coding the current picture using acolor mapping LUT of a second LUT size, wherein the LUT size for thecolor mapping LUT associated with the current picture is determinedbased on comparing the first and second rate-distortion costs.
 30. Themethod of claim 23, further comprising: identifying a temporal level ofthe current picture; and determining whether to disable picture-levelcolor mapping LUT update based on the temporal level of the currentpicture, wherein the picture-level color mapping LUT update is disabledwhen the temporal level of the current picture is high.
 31. A videocoding device comprising: a processor configured to: receive a currentpicture in a video; determine a look-up table (LUT) size of a colormapping LUT for the current picture based on a potential rate-distortioncost; generate the color mapping LUT of the determined LUT size for thecurrent picture; derive, using the color mapping LUT of the LUT size, aninter-layer reference (ILR) picture based on the current picture; andinclude an indication of the determined LUT size for the color mappingLUT associated with the current picture in a bitstream.
 32. The videocoding device of claim 31, wherein the LUT size for the color mappingLUT associated with the current picture is selected from a plurality ofpotential LUT sizes, the processor is further configured to: calculate aplurality of potential rate-distortion costs that correspond to codingthe current picture with the plurality of potential LUT sizes; andselect an optimal LUT size having the smallest rate-distortion cost asthe LUT size for the color mapping LUT associated with the currentpicture.
 33. The video coding device of claim 32, wherein the pluralityof potential LUT sizes are limited by a maximum LUT size, the processoris further configured to: estimate a number of bits for coding thecurrent picture; and determine the maximum LUT size based on theestimated number of bits for coding the current picture.
 34. The videocoding device of claim 31, wherein the processor is further configuredto: identify a temporal level of the current picture; and calculate thepotential rate-distortion cost based on the identified temporal level ofthe current picture, wherein distortion is weighted more heavily for alower temporal level than a higher temporal level.
 35. The video codingdevice of claim 31, wherein the processor is further configured to:identify a temporal level of the current picture; determine a distortionweighting factor based on the temporal level of the current picture; andcalculate the potential rate-distortion cost using the distortionweighting factor such that distortion is weighted more heavily when thetemporal level of the current picture is a low temporal level than whenthe temporal level of the current picture is a high temporal level. 36.The video coding device of claim 31, wherein the processor is furtherconfigured to: generate an enhancement layer picture based on thecurrent picture; determine a usage of the ILR picture in predicting theenhancement layer picture; determine, based on the determined usage ofthe ILR picture, a distortion weighting factor for calculating thepotential rate-distortion cost such that distortion is weighted moreheavily when the ILR picture is used in predicting the enhancement layerpicture.
 37. The video coding device of claim 31, wherein the processoris further configured to: calculate a first rate-distortion costassociated of coding the current picture using a color mapping LUT of afirst LUT size; and calculate a second rate-distortion cost associatedof coding the current picture using a color mapping LUT of a second LUTsize, wherein the LUT size for the color mapping LUT associated with thecurrent picture is determined based on comparing the first and secondrate-distortion costs.
 38. The video coding device of claim 31, whereinthe processor is further configured to: identify a temporal level of thecurrent picture; and determine whether to disable picture-level colormapping LUT update based on the temporal level of the current picture,wherein the picture-level color mapping LUT update is disabled when thetemporal level of the current picture is high.